# Transducer geometry illustrated

The settings from the Platform Properties dialog box and the Transducer Properties dialog box provide the reference points and planes for fish track geometry.

## The Platform: Specifying position and attitude on the earth

### Moving platform

• Specify a GPS data source for Latitude and longitude.
• Can specify X, Y location of the GPS antenna on the platform.
• Can specify an associated Distance data source.
• Can specify a Heading data source.
• Specify Altitude of platform system reference point.

### Fixed platform

• Specify Latitude and longitude.
• Can specify the Fixed heading (North) or a Heading data source.
• Specify Altitude of platform system reference point.

### Z coordinate of the water level

• Specify Z coordinate of the water level in relation to the Altitude of the platform system reference point. The value of the Z coordinate of the water level represents the water level at the start time of the echogram data.

### Heave source

• Specify heave data source for the platform.

Note: Roll and Pitch data are not applied to the platform but may be applied to raw variables.

## The Transducer: Specifying location and orientation on the platform

### Transducer location

X and Y values specify the location of the transducer with respect to the X, Y plane of the platform.

The Z value is the transducer vertical offset with respect to the Altitude of the platform system reference point.

### Transducer orientation

Values for Elevation, Azimuth and Beam rotation describe the orientation of the transducer on the platform.

#### Example: One horizontal transducer on a fixed platform

 Figure 1: Google Map display for the location of a transducer on a fixed platform. Up is North. Figure 2: Schematic (map view) for a fixed platform with a transducer at an Azimuth of 190 degrees.
##### Platform Position and Transducer Location

Platform Position settings

• Fixed platform
• Latitude = 60.518541. Longitude = -151.163664
• Altitude of platform = 0 m.
• Z coordinate of the water level = 0 m.

Transducer Location settings

• Current transducer locations X = 0 m, Y = 0 m is displayed on Figure 3: View from above.
• Current transducer location Z = 0.5 m is displayed on Figure 3: View from east.

Figure 3: One transducer on a fixed platform. Transducer Properties dialog box: Location page.

##### Transducer Orientation

Transducer Orientation settings

• Elevation = 85 degrees is displayed as the yellow transducer near Horizontal on Figure 4: View from transducer.
• Azimuth = 190 degrees is displayed as the red arrow on Figure 4: View from above.
• Beam rotation = 0 degrees is displayed as zero degrees rotation of the yellow transducer on Figure 4: View from transducer.

Figure 4: One transducer on a fixed platform. Transducer Properties dialog box: Orientation page.

##### Scene, Fish track: Direction_horizontal, Direction_vertical
 Figure 5: Map view (up is North) of an imaging sonar ping curtain in a Scene. The beam fan is oriented correctly and located under the water. Figure 6: (Top) Fish tracks in single target echogram derived from multibeam target detection on imaging sonar data. (Bottom) Fish track export data showing Direction_horizontal (degrees) and Direction_vertical (degrees).
##### Planes and reference directions for Direction_horizontal and Direction_vertical

Figure 7: Fixed platform Direction_horizontal and Direction_vertical reference planes and directions.